Systems and methods for intra-surgical monitoring of cochlear trauma during an electrode lead insertion procedure

ABSTRACT

An illustrative system includes a cochlear implant, a lead configured to be inserted into a cochlea of a patient by way of an insertion procedure, a plurality of electrodes disposed on the lead and including an intracochlear electrode and an extracochlear electrode, a probe coupled to the extracochlear electrode, and a processor communicatively coupled with the probe and the cochlear implant. During the insertion procedure, the processor directs the cochlear implant to short the intracochlear and extracochlear electrodes, then detects, by way of the probe and the shorted intracochlear and extracochlear electrodes, evoked responses measured at the intracochlear electrode. The evoked responses include a first evoked response measured at a first insertion depth and a second evoked response measured at a second insertion depth. The processor generates, based on the first and second evoked responses, a notification indicating that cochlear trauma has likely occurred at the second insertion depth.

RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 16/072,780, filed Jul. 25, 2018, which is a U.S.National Stage Application under 35 U.S.C. § 371 of InternationalApplication No. PCT/US20161015203, filed Jan. 27, 2016, the contents ofwhich are hereby incorporated by reference in their respectiveentireties.

BACKGROUND INFORMATION

Insertion of an electrode lead into a cochlea of a cochlear implantpatient is a delicate surgical procedure that can sometimes cause traumaor other harm to the cochlea of the patient. As a result, it may bedesirable for surgeons and/or other professionals assisting with thesurgical insertion procedure to monitor the cochlea during the insertionprocedure to detect trauma to the cochlea in real-time as the insertionprocedure takes place.

In one form of monitoring that is sometimes performed during insertionprocedures, electrocochleographic (“ECoG”) potentials occurring beforeor during the insertion procedure are monitored to track residualhearing of different areas of the cochlea as the electrode lead isinserted. However, because ECoG potentials are conventionally monitoredby an electrode outside of the cochlea (e.g., at the promontory of thetympanic cavity, at the round window within the ear, at the oval windowwithin the ear, etc.) it may be difficult or impossible to positivelydetect cochlear trauma based on ECoG potentials measured at theseconventional placement sites. Moreover, because potentials measuredoutside of the cochlea are smaller than potentials that occur within thecochlea itself, potentials measured outside of the cochlea must bemonitored for a relatively long period of time in order to provideenough averaging to achieve acceptable signal to noise (“SNR”) ratios toderive useful information from the potentials. As a result, cochleartrauma detected from potentials measured from outside of the cochlea maybe relayed to the surgeon performing the insertion procedure withundesirable or unacceptable delays. Finally, placement of an electrodeoutside the cochlea at the promontory of the tympanic cavity, the roundwindow, or the oval window may obstruct the surgeon's view of theelectrode lead during the insertion procedure, further complicating theprocedure and increasing the risk of cochlea trauma.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments and are a partof the specification. The illustrated embodiments are merely examplesand do not limit the scope of the disclosure. Throughout the drawings,identical or similar reference numbers designate identical or similarelements.

FIG. 1 illustrates an exemplary auditory prosthesis system according toprinciples described herein.

FIG. 2 illustrates a schematic structure of the human cochlea accordingto principles described herein.

FIG. 3 illustrates an exemplary implementation of the auditoryprosthesis system of FIG. 1 according to principles described herein.

FIG. 4 illustrates an exemplary configuration in which a programmingsystem is communicatively coupled to a sound processor according toprinciples described herein.

FIG. 5 illustrates an exemplary implementation of a programming systemaccording to principles described herein.

FIG. 6 illustrates exemplary components of a monitoring system accordingto principles described herein.

FIG. 7 illustrates an exemplary implementation of the monitoring systemof FIG. 6 according to principles described herein.

FIG. 8 illustrates an exemplary insertion procedure of an electrode leadinto a cochlea of a patient according to principles described herein.

FIG. 9 illustrates an exemplary graph of evoked responses measured alongthe cochlea during the insertion procedure of FIG. 8 according toprinciples described herein.

FIG. 10 illustrates an exemplary insertion procedure of an electrodelead into a cochlea of a patient according to principles describedherein.

FIG. 11 illustrates an exemplary graph of evoked responses measuredalong the cochlea during the insertion procedure of FIG. 10 according toprinciples described herein.

FIG. 12 illustrates an exemplary insertion procedure of an electrodelead into a cochlea of a patient according to principles describedherein.

FIGS. 13-14 show exemplary graphical user interfaces according toprinciples described herein.

FIG. 15 illustrates an exemplary computing device according toprinciples described herein.

DETAILED DESCRIPTION

Systems and methods for intra-surgical monitoring of cochlear traumaduring an electrode lead insertion procedure are described herein. Forexample, an exemplary monitoring system implemented by at least onephysical computing device may monitor evoked responses that occur inresponse to acoustic stimulation produced at a particular frequencyduring an insertion procedure in which a lead that is communicativelycoupled to a cochlear implant is inserted into a cochlea of a patient.As will be described below, the monitoring of the evoked responses mayinclude using an intracochlear electrode included in a plurality ofintracochlear electrodes disposed on a distal portion of the lead. Theintracochlear electrode may be used to measure a first evoked responseat a first insertion depth of the intracochlear electrode within thecochlea and a second evoked response at a second insertion depth of theintracochlear electrode within the cochlea, the second insertion depthnearer within the cochlea to an apex of the cochlea than the firstinsertion depth.

During the insertion procedure, the monitoring system may determine thata change between the first evoked response measured at the firstinsertion depth and the second evoked response measured at the secondinsertion depth is greater than a predetermined threshold. Then, duringthe insertion procedure and based on the determination that the changeis greater than the predetermined threshold, the monitoring system maydetermine that cochlear trauma has likely occurred at the secondinsertion depth of the intracochlear electrode within the cochlea.

Because an intracochlear electrode is used in accordance with thesystems and methods described herein to detect the evoked responseswithin the cochlea itself, cochlear trauma may be more reliablydetermined to have occurred at more accurate locations within thecochlea as compared to conventional systems and methods involvingmeasuring of the evoked responses from outside the cochlea (e.g., fromthe promontory of the tympanic cavity, the round window, or the ovalwindow). Moreover, the detected evoked responses may have much higheramplitudes than evoked responses detected at extracochlear locations,resulting in faster processing of the evoked responses and allowingfeedback related to cochlear trauma caused by the insertion procedure tobe relayed to a surgeon performing the insertion procedure insubstantially real-time as the electrode lead is inserted. Additionally,the systems and methods described herein do not require an additionalrecording electrode not disposed on the electrode lead and that mightobstruct the surgeon's view of the electrode lead during the insertionprocedure.

As used herein, an “evoked response” cochlear microphonics, an auditorynerve response, a brainstem response, a compound action potential, anECoG potential, and/or any other type of neural or physiologicalresponse that may occur within a patient in response to application ofacoustic stimulation to the patient. For example, evoked responses mayoriginate from neural tissues, hair cell to neural synapses, inner orouter hair cells, or other sources.

FIG. 1 illustrates an exemplary auditory prosthesis system 100. Auditoryprosthesis system 100 may include a microphone 102, a sound processor104, a headpiece 106 having a coil disposed therein, a cochlear implant108, and an electrode lead 110 (also referred to as a “lead”). Lead 110includes an array of intracochlear electrodes 112 disposed on a distalportion of lead 110 and that are configured to be located within thecochlea after lead 110 is inserted into the cochlea. While lead 110 isshown to be straight, it will be recognized that lead 110 mayalternatively be pre-curved so as to fit within the cochlea. Additionalor alternative components may be included within auditory prosthesissystem 100 as may serve a particular implementation.

As shown, auditory prosthesis system 100 may include various componentsconfigured to be located external to a patient including, but notlimited to, microphone 102, sound processor 104, and headpiece 106.Auditory prosthesis system 100 may further include various componentsconfigured to be implanted within the patient including, but not limitedto, cochlear implant 108 and electrode lead 110.

Microphone 102 may be configured to detect audio signals presented tothe user. Microphone 102 may be implemented in any suitable manner. Forexample, microphone 102 may include a microphone that is configured tobe placed within the concha of the ear near the entrance to the earcanal, such as a T-MIC™ microphone from Advanced Bionics. Such amicrophone may be held within the concha of the ear near the entrance ofthe ear canal by a boom or stalk that is attached to an ear hookconfigured to be selectively attached to sound processor 104.Additionally or alternatively, microphone 102 may be implemented by oneor more microphones disposed within headpiece 106, one or moremicrophones disposed within sound processor 104, one or morebeam-forming microphones, and/or any other suitable microphone as mayserve a particular implementation.

Sound processor 104 (i.e., one or more components included within soundprocessor 104) may be configured to direct cochlear implant 108 togenerate and apply electrical stimulation (also referred to herein as“stimulation current”) representative of one or more audio signals(e.g., one or more audio signals detected by microphone 102, input byway of an auxiliary audio input port, input by way of a CPI, etc.) toone or more stimulation sites associated with an auditory pathway (e.g.,the auditory nerve) of the patient. Exemplary stimulation sites include,but are not limited to, one or more locations within the cochlea, thecochlear nucleus, the inferior colliculus, and/or any other nuclei inthe auditory pathway. To this end, sound processor 104 may process theone or more audio signals in accordance with a selected sound processingstrategy or program to generate appropriate stimulation parameters forcontrolling cochlear implant 108. Sound processor 104 may be housedwithin any suitable housing (e.g., a behind-the-ear (“BTE”) unit, a bodyworn device, and/or any other sound processing unit as may serve aparticular implementation).

In some examples, sound processor 104 may wirelessly transmitstimulation parameters (e.g., in the form of data words included in aforward telemetry sequence) and/or power signals to cochlear implant 108by way of a wireless communication link 114 between headpiece 106 andcochlear implant 108 (e.g., a wireless link between a coil disposedwithin headpiece 106 and a coil physically coupled to cochlear implant108). It will be understood that communication link 114 may include abi-directional communication link and/or one or more dedicateduni-directional communication links.

Headpiece 106 may be communicatively coupled to sound processor 104 andmay include an external antenna (e.g., a coil and/or one or morewireless communication components) configured to facilitate selectivewireless coupling of sound processor 104 to cochlear implant 108.Headpiece 106 may additionally or alternatively be used to selectivelyand wirelessly couple any other external device to cochlear implant 108.To this end, headpiece 106 may be configured to be affixed to thepatient's head and positioned such that the external antenna housedwithin headpiece 106 is communicatively coupled to a correspondingimplantable antenna (which may also be implemented by a coil and/or oneor more wireless communication components) included within or otherwiseassociated with cochlear implant 108. In this manner, stimulationparameters and/or power signals may be wirelessly transmitted betweensound processor 104 and cochlear implant 108 via a communication link114 (which may include a bi-directional communication link and/or one ormore dedicated uni-directional communication links as may serve aparticular implementation).

Cochlear implant 108 may include any type of implantable stimulator thatmay be used in association with the systems and methods describedherein. For example, cochlear implant 108 may be implemented by animplantable cochlear stimulator. In some alternative implementations,cochlear implant 108 may include a brainstem implant and/or any othertype of cochlear implant that may be implanted within a patient andconfigured to apply stimulation to one or more stimulation sites locatedalong an auditory pathway of a patient.

In some examples, cochlear implant 108 may be configured to generateelectrical stimulation representative of an audio signal processed bysound processor 104 (e.g., an audio signal detected by microphone 102)in accordance with one or more stimulation parameters transmittedthereto by sound processor 104. Cochlear implant 108 may be furtherconfigured to apply the electrical stimulation to one or morestimulation sites (e.g., one or more intracochlear regions) within thepatient via one or more intracochlear electrodes 112 disposed alongelectrode lead 110. In some examples, cochlear implant 108 may include aplurality of independent current sources each associated with a channeldefined by one or more of intracochlear electrodes 112. In this manner,different stimulation current levels may be applied to multiplestimulation sites simultaneously by way of multiple intracochlearelectrodes 112.

FIG. 2 illustrates a schematic structure of the human cochlea 200 intowhich electrode lead 110 may be inserted. As shown in FIG. 2, cochlea200 is in the shape of a spiral beginning at a base 202 and ending at anapex 204. Within cochlea 200 resides auditory nerve tissue 206, which isdenoted by Xs in FIG. 2. The auditory nerve tissue 206 is organizedwithin the cochlea 200 in a tonotopic manner. Relatively low frequenciesare encoded at or near the apex 204 of the cochlea 200 (referred to asan “apical region”) while relatively high frequencies are encoded at ornear the base 202 (referred to as a “basal region”). Hence, electricalstimulation applied by way of electrodes disposed within the apicalregion (i.e., “apical electrodes”) may result in the patient perceivingrelatively low frequencies and electrical stimulation applied by way ofelectrodes disposed within the basal region (i.e., “basal electrodes”)may result in the patient perceiving relatively high frequencies. Thedelineation between the apical and basal electrodes on a particularelectrode lead may vary depending on the insertion depth of theelectrode lead, the anatomy of the patient's cochlea, and/or any otherfactor as may serve a particular implementation.

The auditory prosthesis system 100 illustrated in FIG. 1 may be referredto as a cochlear implant system because sound processor 104 isconfigured to direct cochlear implant 108 to generate and applyelectrical stimulation representative of audio content (e.g., one ormore audio signals) to one or more stimulation sites within the patientby way of one or more of electrodes 112.

FIG. 3 illustrates an exemplary implementation 300 of auditoryprosthesis system 100 in which auditory prosthesis system 100 is furtherconfigured to provide acoustic stimulation to the patient. Hence,implementation 300 shown in FIG. 3 may be referred to as anelectro-acoustic stimulation (“EAS”) system.

As shown, implementation 300 may further include a loudspeaker 302 (alsoreferred to as a “receiver”). Loudspeaker 302 may be in communicationwith an ear of the patient (e.g., located at an entrance or within theear canal of the patient). In this configuration, sound processor 104(which, in implementation 300, may be referred to as an “EAS soundprocessor”) may be configured to direct loudspeaker 302 to applyacoustic stimulation representative of audio content to one or morestimulation sites within the patient (e.g., within cochlea 200,described above in relation to FIG. 2). For example, as will bedescribed in more detail below, loudspeaker 302 may generate acousticstimulation at a particular frequency targeted to be encoded at aparticular location (e.g., at a particular target depth) within thecochlea.

In some examples, loudspeaker 302 may generate acoustic stimulationrepresentative of audio content included in relatively low frequencybands, while cochlear implant 108 may be used to apply electricalstimulation representative of audio content included in relatively highfrequency bands to one or more stimulation sites within the patient byway of one or more of intracochlear electrodes 112.

In some examples, a programming system separate from (i.e., not includedwithin) auditory prosthesis system 100 may be selectively andcommunicatively coupled to sound processor 104 in order to perform oneor more programming or fitting operations with respect to auditoryprosthesis system 100. For example, the programming system may presentaudio clips to the patient by way of the auditory prosthesis system inorder to facilitate evaluation of how well the auditory prosthesissystem is performing for the patient.

To illustrate, FIG. 4 shows an exemplary configuration 400 in which aprogramming system 402 is communicatively coupled (e.g., by way of awired or wireless communication channel) to sound processor 104.Programming system 402 may be implemented by any suitable combination ofphysical computing and communication devices including, but not limitedto, a fitting station or device, a programming device, a personalcomputer, a laptop computer, a handheld device, a mobile device (e.g., amobile phone), a clinician's programming interface (“CPI”) device,and/or any other suitable component as may serve a particularimplementation. In some examples, programming system 402 may provide oneor more graphical user interfaces (“GUIs”) (e.g., by presenting the oneor more GUIs by way of a display screen) with which a clinician or otheruser may interact.

Programming system 402 may be separate from (i.e., not included within)auditory prosthesis system 100 and may be selectively andcommunicatively coupled (e.g., by way of a wired or wirelesscommunication channel) to sound processor 104 in order to perform one ormore programming or fitting operations with respect to auditoryprosthesis system 100. For example, programming system 402 may presentaudio clips to the patient by way of the auditory prosthesis system inorder to facilitate evaluation of how well the auditory prosthesissystem is performing for the patient.

Programming system 402 may be implemented by any suitable combination ofphysical computing and communication devices including, but not limitedto, a fitting station or device, a programming device, a personalcomputer, a laptop computer, a handheld device, a mobile device (e.g., amobile phone), a clinician's programming interface (“CPI”) device,and/or any other suitable component as may serve a particularimplementation. As will be described below, in some examples,programming system 402 may provide one or more graphical user interfaces(“GUIs”) (e.g., by presenting the one or more GUIs by way of a displayscreen) with which a clinician or other user may interact.

FIG. 5 illustrates an exemplary configuration 500 in which programmingsystem 402 is implemented by a computing device 502 and a CPI device504. As shown, computing device 502 may be selectively andcommunicatively coupled to CPI device 504 by way of a cable 506.Likewise, CPI device 504 may be selectively and communicatively coupledto sound processor 104 by way of a cable 508. Cables 506 and 508 mayeach include any suitable type of cable that facilitates transmission ofdigital data between computing device 502 and sound processor 104. Forexample, cable 506 may include a universal serial bus (“USB”) cable andcable 508 may include any type of cable configured to connect to aprogramming port included in sound processor 104.

FIG. 6 illustrates exemplary components of a monitoring system 600.Monitoring system 600 may be configured to perform any of the operationsdescribed herein. As shown, monitoring system 600 may include amonitoring facility 602 and a storage facility 604, which may be incommunication with one another using any suitable communicationtechnologies. Storage facility 604 may maintain monitoring data 606generated and/or used by monitoring facility 602. Storage facility 604may maintain additional or alternative data as may serve a particularimplementation.

Monitoring facility 602 may perform various operation associated withintra-surgical monitoring of cochlear trauma during an electrode leadinsertion procedure.

For example, monitoring facility 602 may monitor evoked responses thatoccur in response to acoustic stimulation produced at a particularfrequency during an insertion procedure in which a lead that iscommunicatively coupled to a cochlear implant is inserted into a cochleaof a patient. Monitoring facility 602 may monitor the evoked responsesusing any suitable equipment and in any way that may serve a particularimplementation. For example, the monitoring of the evoked responses maybe performed using an intracochlear electrode included in a plurality ofintracochlear electrodes disposed on a distal portion of the lead. Aswill be described in more detail below, the intracochlear electrode maybe shorted with an extracochlear electrode communicatively coupled witha probe that is also communicatively coupled with monitoring facility602. As such, the intracochlear electrode may measure a first evokedresponse at a first insertion depth of the intracochlear electrodewithin the cochlea and a second evoked response at a second insertiondepth of the intracochlear electrode within the cochlea (e.g., aninsertion depth nearer to the apex of the cochlea) and may transmit themeasurements to monitoring facility 602 via the extracochlear electrodeand/or the probe.

Monitoring facility 602 may also determine, during the insertionprocedure, that a change between the first evoked response measured atthe first insertion depth and the second evoked response measured at thesecond insertion depth is greater than a predetermined threshold. Forexample, as will be discussed in more detail below, if the particularfrequency of the acoustic stimulation is relatively low (e.g., encodeddeeper within the cochlea than the lead will extend after the insertionprocedure is completed), the second evoked response measured at thesecond insertion depth may be measured to be less than the first evokedresponse by an amount larger than the predetermined threshold.Additionally, if the particular frequency of the acoustic stimulation isrelatively high (e.g., encoded within the cochlea at a depth that thelead will extend past after the insertion procedure is completed), thesecond evoked response measured at the second insertion depth may bemeasured to be less than the first evoked response by an amount largerthan the predetermined threshold combined with an expected decreasebased on the frequency (e.g., a decrease of 1/e microvolts for eachmillimeter beyond a target depth corresponding with the particularfrequency).

During the insertion procedure (e.g., in or near real-time), monitoringfacility 602 may also determine that cochlear trauma has likely occurredat the second insertion depth of the intracochlear electrode within thecochlea based on the determination that the change is greater than thepredetermined threshold. In some examples, cochlear trauma may bedetected based on a change in the phase of the second evoked response ascompared to the phase of the first evoked response in addition to or asan alternative to a change in the amplitude of the second evokedresponse. Various methods of detecting cochlear trauma based on changesin amplitude or phase of evoked responses will be described in moredetail below.

In various embodiments, monitoring facility 602 may perform these andvarious other operations that facilitate the monitoring of cochleartrauma using any component that may serve a particular implementation.For example, monitoring facility 602 may receive a user input commandfrom a user to begin monitoring the evoked responses, present theacoustic stimulation to the patient by way of a loudspeaker (e.g.,loudspeaker 302 of FIG. 3), direct a cochlear implant (e.g., cochlearimplant 108 of FIG. 3) to short a particular intracochlear electrode(e.g., one of intracochlear electrodes 112) with an extracochlearelectrode, receive evoked responses detected and sent by the shortedintracochlear electrode by way of the extracochlear electrode and aprobe, convert signals representative of evoked responses from analogsignals into digital signals, record signals representative of evokedresponses (e.g., digital signals that have been converted from analogsignals recorded by the intracochlear electrode), notify a user thatcochlear trauma has likely occurred, and perform any other step that mayserve a particular implementation.

To illustrate, FIG. 7 shows an exemplary implementation 700 ofmonitoring system 600 in which monitoring system 600 is at leastpartially implemented by programming system 402 and sound processor 104included in an EAS system.

As shown in FIG. 7, sound processor 104 is physically andcommunicatively coupled to loudspeaker 302. As also shown in FIG. 7, anextracochlear electrode 702 may be physically and communicativelycoupled to a probe 704 by way of a clip connection 706 that may beremovably (i.e., temporarily) connected to extracochlear electrode 702.

Extracochlear electrode 702 may be included on lead 110 along withintracochlear electrodes 112. However, unlike intracochlear electrodes112, extracochlear electrode 702 may be configured to be locatedexternal to the cochlea after insertion of lead 110. As such,extracochlear electrode 702 may be used, in some examples, as a returnelectrode for electrical stimulation applied via one or more ofintracochlear electrodes 112. As will be described in more detail below,extracochlear electrode 702 may facilitate monitoring of evokedresponses from within the cochlea by intracochlear electrodes 112. Insome examples, extracochlear electrode 702 may comprise a ringelectrode.

Probe 704 may be communicatively coupled to sound processor 104 in anysuitable manner. For example, as shown in FIG. 7, a distal end of probe704 may be physically and communicatively coupled to an amplifier 708.Amplifier 708, in turn, may be communicatively coupled to soundprocessor 104 by way of a communication channel 710, which may be wiredor wireless. It will be recognized that amplifier 708 may, in someembodiments, be omitted from implementation 700. In these cases, probe704 may be physically coupled directly to sound processor 104.

In some examples, a user of monitoring system 600 may provide a userinput command for monitoring system 600 to begin monitoring evokedresponses that occur in response to acoustic stimulation during aninsertion procedure in which lead 110 is inserted into a cochlea of apatient. As described above, lead 110 may be physically andcommunicatively coupled to cochlear implant 108 during the insertionprocedure. In response to the user input command, monitoring system 600may begin monitoring the evoked responses as described below.

Programming system 402 may receive the user input command in anysuitable manner. For example, programming system 402 may present agraphical user interface (e.g., by displaying the graphical userinterface on a display screen) during the insertion procedure. Thegraphical user interface may include a selectable option to beginmonitoring for the evoked responses. A user may select the option toprovide the user input command. Specific examples of graphical userinterfaces presented by programming system 402 will be described in moredetail below.

Programming system 402 may transmit the user input command to soundprocessor 104. In response to receiving the user input command, soundprocessor 104 may direct cochlear implant 108 to short an intracochlearelectrode included in the array of intracochlear electrodes 112 withextracochlear electrode 702. For example, sound processor 104 may directcochlear implant 108 to short an intracochlear electrode 112-1 that isthe most distal intracochlear electrode 112 of lead 110 withextracochlear electrode 702. In other examples, sound processor 104 maydirect cochlear implant 108 to short any one of the other intracochlearelectrodes 112 with extracochlear electrode 702 as may serve aparticular implementation. Directing cochlear implant 108 to shortintracochlear electrode 112-1 with extracochlear electrode 702 may beperformed by transmitting a command to cochlear implant 108 by way of awireless link that communicatively couples sound processor 104 andcochlear implant 108 (e.g., communication link 114).

In response to receiving the command from sound processor 104, cochlearimplant 108 may short intracochlear electrode 112-1 with extracochlearelectrode 702. Cochlear implant 108 may short intracochlear electrode112-1 with extracochlear electrode 702 in any suitable manner. Forexample, cochlear implant 108 may utilize a multiplexer included withincochlear implant 108 to short intracochlear electrode 112-1 withextracochlear electrode 702. While intracochlear electrode 112-1 andextracochlear electrode 702 are shorted together, sound processor 104may present acoustic stimulation by way of loudspeaker 302. The acousticstimulation may include any suitable acoustic stimulation (e.g., one ormore tones).

Sound processor 104 may record evoked responses that occur in responseto the acoustic stimulation. For example, sound processor 104 mayreceive, by way of extracochlear electrode 702 and probe 704, signalsrepresentative of the evoked responses as detected and sent byintracochlear electrode 112-1. The signals detected and sent byintracochlear electrode 112-1 may be analog signals. Hence, in someexamples, sound processor 104 may convert the detected analog signals todigital signals by using an analog-to-digital converter included insound processor 104 and that is also used by sound processor 104 toconvert analog audio signals detected by microphone 102 into digitalaudio signals.

In some examples, sound processor 104 may transmit the digital signalsrepresentative of the evoked responses to programming system 402.Programming system 402 may use the digital signals to generate andpresent, within a graphical user interface, graphical informationassociated with the evoked responses. For example, as will be describedin more detail below, the graphical information may include a graph thatrepresents amplitudes of the evoked responses, a graph that represents acurrent time domain waveform of the evoked responses, and/or a graphthat represents a current frequency domain waveform of the evokedresponses.

In some examples, the signals detected by intracochlear electrode 112-1may be amplified by amplifier 708 prior to sound processor 104 receivingthe detected signals. For example, amplifier 708 may receive thedetected signals by way of extracochlear electrode 114 and probe 704.Amplifier 708 may amplify the detected signals, which may result in aplurality of amplified signals. Amplifier 708 may transmit the amplifiedsignals to sound processor 104 by way of communication channel 710. Byamplifying the signals detected by intracochlear electrode 112-1,amplifier 708 may enable sound processor 104 to more effectively andefficiently process the signals. For example, amplification by amplifier708 may make the signals large enough to be accurately converted fromthe analog domain to the digital domain. It will be recognized thatalthough amplifier 708 is shown to be a stand-alone unit located outsidesound processor 104, amplifier 708 may alternatively be located withinsound processor 104.

As will be described in more detail below in relation to FIGS. 8-12,while lead 110 is being inserted into the cochlea and while evokedresponses are being monitored (e.g., by implementation 700 as describedabove), a first evoked response at a first insertion depth ofintracochlear electrode 112-1 and a second evoked response at a secondinsertion depth of intracochlear electrode 112-1 (e.g., an insertiondepth nearer within the cochlea to an apex of the cochlea than the firstinsertion depth) may be measured in any of the ways described herein.Based on the measurements, monitoring system 600 (e.g., includingprogramming system 402 and/or sound processor 104) may determine that achange between the first evoked response and the second evoked responseis greater than a predetermined threshold, and may further determinethat that cochlear trauma has likely occurred at the second insertiondepth of the intracochlear electrode within the cochlea. Based on thesedeterminations, monitoring system 600 may notify (e.g., by an audiblesound, a visible warning light, a message displayed on a graphical userinterface presented by programming system 402, etc.) a user ofmonitoring system 600 that cochlear trauma has likely occurred at thesecond insertion depth of the intracochlear electrode within thecochlea.

As illustrated in FIG. 7, sound processor 104 may both present acousticstimulation and record the evoked responses that occur in response tothe acoustic stimulation. However, it will be understood that in otherimplementations of monitoring system 600, sound processor 104 andprogramming system 402 may operate in conjunction with one another inany suitable way to perform these actions and other actions describedabove. For example, sound processor 104 may present the acousticstimulation while programming system 402 may record the evoked responsesthat occur in response to the acoustic stimulation. In another example,programming system 402 may present the acoustic stimulation while soundprocessor 104 may record the evoked responses that occur in response tothe acoustic stimulation. In yet another example, programming system 402may both present the acoustic stimulation and record the evokedresponses that occur in response to the acoustic stimulation. In variousembodiments, other devices may operate in conjunction with soundprocessor 104 and/or programming system 402 to perform any of the tasksdescribed herein. For example, an evoked potential (“EP”) machine (notexplicitly shown in FIG. 7) may be configured to present the acousticstimulation, to record the evoked responses that occur in response tothe acoustic stimulation, or both.

Programming system 600 (e.g., embodied in implementation 700 or inanother suitable implementation as described above) may monitor cochleartrauma in any suitable manner. Various examples of monitoring cochleartrauma will now be described in relation to various insertion proceduresof a lead into a cochlea of a patient.

For example, FIG. 8 illustrates an exemplary insertion procedure 800 oflead 110 into a cochlea 802 of a patient. Cochlea 802 may be a crosssection view of certain regions of auditory nerve tissue surrounding aninner portion of a human cochlea similar to cochlea 200, described abovein relation to FIG. 2. For the sake of clarity in FIG. 8, cochlea 802 isillustrated to be uncoiled such that cochlea 802 does not exhibit thespiral shape shown for cochlea 200. However, it will be understood thatcochlea 802 and lead 110 may be coiled into a spiral shape (e.g.,similar to the shape shown in relation to cochlea 200) during insertionprocedure 800.

It will also be understood, as mentioned above, that lead 110 may beincluded within a monitoring system (e.g., monitoring system 600 of FIG.6 as implemented in implementation 700 of FIG. 7) during insertionprocedure 800. For example, while omitted in FIG. 8 for clarity, lead110 may include an extracochlear electrode (e.g., extracochlearelectrode 702) that may be communicatively coupled with a probe (e.g.,probe 704) by way of a clip connection (e.g., clip connection 706) thatmay be removably connected to the extracochlear electrode as discussedabove in relation to FIG. 7. Additionally, lead 110 may becommunicatively coupled with a cochlear implant (e.g., cochlear implant108 in FIG. 7) which may receive direction from a sound processor (e.g.,sound processor 104 in FIG. 7) and/or from a programming system (e.g.,programming system 402 in FIG. 7), which may also be generating acousticstimulation at a particular frequency (e.g., using loudspeaker 302 inFIG. 7) as described above. As such, one of intracochlear electrodes 112(e.g., intracochlear electrode 112-1) may be shorted with theextracochlear electrode and may communicate evoked responses measuredwithin cochlea 802 to the sound processor and/or to the programmingsystem via the extracochlear electrode, the probe, and/or othercomponents of the monitoring system (e.g., an amplifier such asamplifier 708 in FIG. 7) that may serve a particular implementation.

As shown in FIG. 8, cochlea 802 may begin at a base 804, which may besimilar to base 202 of cochlea 200 in FIG. 2, and may end at an apex806, which may be similar to apex 204 of cochlea 200. Insertionprocedure 800 is represented by an arrow indicating a direction thatlead 110 may be inserted into cochlea 802 during insertion procedure800. During insertion procedure 800, lead 110 may be inserted intocochlea 802 beginning from outside base 804 until lead 110 reaches afinal insertion depth 808, illustrated as a dotted line extendingthrough cochlea 802. Accordingly, in FIG. 8, lead 110 is shown to bepartially, but not fully, inserted into cochlea 802, indicating thatinsertion procedure 800 is ongoing.

As mentioned above, acoustic stimulation produced at a particularfrequency (e.g., a tone at the particular frequency) may be generated(e.g., by a loudspeaker such as loudspeaker 302 in FIG. 7) duringinsertion procedure 800. Due to the tonotopic organization of auditorynerve tissue within cochlea 802 (see description in FIG. 2, above), theparticular frequency may be encoded by auditory nerve tissue at aspecific location (e.g., at a specific depth) within cochlea 802. Forexample, the auditory nerve tissue that encodes the particular frequencygenerated in the example of insertion procedure 800 may be encoded byauditory nerve tissue denoted by Xs in FIG. 8. Because the particularfrequency in this example may be a relatively low frequency (e.g., 250Hz), the auditory nerve tissue that encodes the particular frequencywithin cochlea 802 may correspond to (e.g., may be located at) a lowfrequency target depth 810 of cochlea 802. As shown, low frequencytarget depth 810 may be located nearer within cochlea 802 to apex 806 ofcochlea 802 than final insertion depth 808. In other words, lead 110,including intracochlear electrode 112-1, may not pass or even reach lowfrequency target depth 810 during insertion procedure 800.

During insertion procedure 800, monitoring system 600 may monitor evokedresponses that occur within cochlea 802 in response to the acousticstimulation produced at the particular frequency (e.g., the relativelylow frequency encoded by auditory nerve tissue located at low frequencytarget depth 810). More specifically, monitoring system 600 may useintracochlear electrode 112-1 to measure a first evoked response at afirst insertion depth 812-1 and a second evoked response at a secondinsertion depth 812-2. As shown, second insertion depth 812-2 may benearer within cochlea 802 to apex 806 (i.e. nearer according to a curvedroute traveled by acoustic waves through cochlea 802 rather thanaccording to a straight route cutting directly through walls of cochlea802) than first insertion depth 812-1.

Based on the measurements of the evoked responses at first and secondinsertion depths 812 and while insertion procedure 800 is still ongoing,monitoring system 600 may determine that a change between the firstevoked response measured at first insertion depth 812-1 and the secondevoked response measured at second insertion depth 812-2 is greater thana predetermined threshold. For example, monitoring system 600 maydetermine that the second evoked response is smaller in amplitude thanthe first evoked response by an amount greater than the predeterminedthreshold.

To illustrate, FIG. 9 shows an exemplary graph 900 of evoked responsecurves 902 and 904 measured along cochlea 802 during insertion procedure800. In graph 900, evoked response curves 902 and 904 are illustratedwith a horizontal axis (i.e. an x-axis) representing cochlear depthwithin cochlea 802 (e.g., measured in millimeters (“mm”)). Thus, tocorrespond to FIG. 8, points representing first insertion depth 812-1,second insertion depth 812-2, final insertion depth 808, and lowfrequency target depth 810 are shown along the horizontal axis from leftto right in that order. Evoked response curves 902 and 904 areillustrated with a vertical axis (i.e. a y-axis) representing a responseamplitude of the evoked response curves (e.g., measured in microvolts(“uV”)). Accordingly, graph 900 illustrates how the amplitude of evokedresponses (e.g., theoretical or measured evoked responses) withincochlea 802 may vary with cochlear depth (e.g., with the depth at whichintracochlear electrode 112-1 is located within cochlea 802) duringinsertion procedure 800.

In FIG. 9, evoked response curve 902 may correspond to a theoretical(e.g., an ideal) evoked response curve representative of what monitoringsystem 600 would monitor in an ideal insertion procedure where nocochlear trauma is inflicted on cochlea 802. As shown, the responseamplitude of evoked response curve 902 continues to increase as thecochlear depth of intracochlear electrode 112-1 increases. If monitoringsystem 600 monitors a continuously increasing evoked response curve suchas evoked response curve 902, a surgeon performing insertion procedure800 may know or assume that insertion procedure 800 has not causedcochlear trauma to cochlea 802 within the patient.

Conversely, evoked response curve 904 may correspond to a measuredevoked response curve representative of what monitoring system 600actually monitors during insertion procedure 800. As shown, the responseamplitude of evoked response curve 904 begins to decrease at aparticular cochlear depth (e.g., around first insertion depth 812-1) asthe cochlear depth of intracochlear electrode 112-1 increases (e.g., aslead 110 is inserted into cochlea 802). Specifically, at first insertiondepth 812-1, monitoring system 600 may monitor a first evoked response906-1, while at second insertion depth 812-2, monitoring system 600 maymonitor a second evoked response 906-2 that is smaller in amplitude thanfirst evoked response 906-1. If a change 908 between first evokedresponse 906-1 and second evoked response 906-2 is greater than apredetermined threshold (e.g., 0 uV, 1 uV, 10 uV, etc.), monitoringsystem 600 may determine that cochlear trauma has likely occurred at aparticular cochlear depth between first insertion depth 812-1 and secondinsertion depth 812-2. For example, monitoring system 600 may determinethat cochlear trauma has likely occurred at second insertion depth812-2. As described above in relation to FIG. 7, monitoring system 600may, in response to detecting the likely cochlear trauma, notify a userof monitoring system 600 (e.g., the surgeon performing insertionprocedure 800) that cochlear trauma has likely occurred at theparticular cochlear depth between first insertion depth 812-1 and secondinsertion depth 812-2 (e.g., at second insertion depth 812-2) withincochlea 802.

As another example of monitoring cochlear trauma, FIG. 10 illustrates anexemplary insertion procedure 1000 of lead 110 into cochlea 802 of thepatient. As explained above in relation to FIG. 8, in FIG. 10, lead 110may be included in a monitoring system (e.g., monitoring system 600 ofFIG. 6 as implemented in implementation 700 of FIG. 7) during insertionprocedure 1000. Again, while omitted in FIG. 10 for clarity, lead 110may include an extracochlear electrode (e.g., extracochlear electrode702) that may be communicatively coupled with a probe (e.g., probe 704)by way of a clip connection (e.g., clip connection 706) that may beremovably connected to the extracochlear electrode as discussed above inrelation to FIG. 7. Additionally, lead 110 may be communicativelycoupled with a cochlear implant (e.g., cochlear implant 108 in FIG. 7)which may receive direction from a sound processor (e.g., soundprocessor 104 in FIG. 7) and/or from a programming system (e.g.,programming system 402 in FIG. 7), which may also be generating acousticstimulation at a particular frequency (e.g., using loudspeaker 302 inFIG. 7) as described above. As such, one of intracochlear electrodes 112(e.g., intracochlear electrode 112-1) may be shorted with theextracochlear electrode and may communicate evoked responses measuredwithin cochlea 802 to the sound processor and/or to the programmingsystem via the extracochlear electrode, the probe, and/or othercomponents of the monitoring system (e.g., an amplifier such asamplifier 708 in FIG. 7) that may serve a particular implementation.

Insertion procedure 1000 is represented by an arrow indicating adirection that lead 110 may be inserted into cochlea 802 duringinsertion procedure 1000. During insertion procedure 1000, lead 110 maybe inserted into cochlea 802 beginning from outside base 804 until lead110 reaches final insertion depth 808, illustrated as a dotted lineextending through cochlea 802. Accordingly, in FIG. 10, lead 110 isshown to be partially, but not fully, inserted into cochlea 802,indicating that insertion procedure 1000 is ongoing.

As in previous examples, acoustic stimulation produced at a particularfrequency (e.g., a tone at the particular frequency) may be generated(e.g., by a loudspeaker such as loudspeaker 302 in FIG. 7) duringinsertion procedure 1000. However, the particular frequency generated inthe example of insertion procedure 1000 may be different (e.g., higher)than the particular frequency generated in other examples describedherein. Due to the tonotopic organization of auditory nerve tissuewithin cochlea 802 (see description in FIG. 2, above), the particularfrequency generated for insertion procedure 1000 may be encoded byauditory nerve tissue at a specific location (e.g., at a specific depth)within cochlea 802. For example, the auditory nerve tissue that encodesthe particular frequency generated may be encoded by auditory nervetissue denoted by Xs in FIG. 10. Because the particular frequency usedfor insertion procedure 1000 may be a relatively high frequency (e.g.,1000 Hz), the auditory nerve tissue that encodes the particularfrequency within cochlea 802 may correspond to (e.g., may be located at)a high frequency target depth 1002 of cochlea 802. As shown, highfrequency target depth 1002 may be located farther within cochlea 802from apex 806 of cochlea 802 than final insertion depth 808. In otherwords, lead 110, including intracochlear electrode 112-1, may reach andthen pass high frequency target depth 1002 during insertion procedure1000.

During insertion procedure 1000, monitoring system 600 may monitorevoked responses that occur within cochlea 802 in response to theacoustic stimulation produced at the particular frequency (e.g., therelatively high frequency encoded by auditory nerve tissue located athigh frequency target depth 1002). More specifically, monitoring system600 may use intracochlear electrode 112-1 to measure a first evokedresponse at a first insertion depth 1004-1 and a second evoked responseat a second insertion depth 1004-2. As shown, second insertion depth1004-2 may be nearer within cochlea 802 to apex 806 (i.e. neareraccording to a curved route traveled by acoustic waves through cochlea802 rather than according to a straight route cutting directly throughwalls of cochlea 802) than first insertion depth 1004-1.

Based on the measurements of evoked responses at first and secondinsertion depths 1004 and while insertion procedure 1000 is stillongoing, monitoring system 600 may determine that a change between thefirst evoked response measured at first insertion depth 1004-1 and thesecond evoked response measured at second insertion depth 1004-2 isgreater than a predetermined threshold. For example, monitoring system600 may determine that the second evoked response is smaller inamplitude than the first evoked response by an amount greater than thepredetermined threshold combined with an expected decrease in the secondevoked response for each unit of distance beyond high frequency targetdepth 1002 that second insertion depth 1004-2 is located.

To illustrate, FIG. 11 shows an exemplary graph 1100 of evoked responsecurves 1102 and 1104 measured along cochlea 802 during insertionprocedure 1000. In graph 1100, evoked response curves 1102 and 1104 areillustrated with a horizontal axis (i.e. an x-axis) representingcochlear depth within cochlea 802 (e.g., measured in mm). Thus, tocorrespond to FIG. 10, points representing high frequency target depth1002, first insertion depth 1004-1, second insertion depth 1004-2, andfinal insertion depth 808 are shown along the horizontal axis from leftto right in that order. Evoked response curves 1102 and 1104 areillustrated with a vertical axis (i.e. a y-axis) representing a responseamplitude of the evoked response curves (e.g., measured in uV).Accordingly, graph 1100 illustrates how the amplitude of evokedresponses (e.g., theoretical or measured evoked responses) withincochlea 802 may vary with cochlear depth (e.g., with the depth at whichintracochlear electrode 112-1 is located within cochlea 802) duringinsertion procedure 1000.

In FIG. 11, evoked response curve 1102 may correspond to a theoretical(e.g., an ideal) evoked response curve representative of what monitoringsystem 600 would monitor in an ideal insertion procedure where nocochlear trauma is generated on cochlea 802. As shown, the responseamplitude of evoked response curve 1102 continues to increase as thecochlear depth of intracochlear electrode 112-1 increases up until highfrequency target depth 1002. Then, as evoked response amplitudes aremonitored at cochlear depths beyond high frequency target depth 1002,the response amplitude of evoked response curve 1102 decreases at anexpected decrease rate 1106. For example, expected decrease rate 1106may be approximately equal to 1/e uV/mm, where e is Euler's number(approximately equal to 2.718). Thus, expected decrease rate 1106 may beapproximately equal to 0.368 uV/mm and evoked response curve 1102 maydecrease approximately in parallel with expected decrease rate 1106 asshown in graph 1100. If monitoring system 600 monitors an evokedresponse curve that continuously increases up until high frequencytarget depth 1002 and decreases at expected decrease rate 1106thereafter such as evoked response curve 1102, a surgeon performinginsertion procedure 1000 may know or assume that insertion procedure1000 has not caused cochlear trauma to cochlea 802 within the patient.

Conversely, evoked response curve 1104 may correspond to a measuredevoked response curve representative of what monitoring system 600actually monitors during insertion procedure 1000. Like evoked responsecurve 1102, the response amplitude of evoked response curve 1104increases as the cochlear depth increases up until high frequency targetdepth 1002, whereupon the response amplitude of evoked response curve1104 begins to decrease. However, unlike evoked response curve 1102,which decreases at approximately expected decrease rate 1106, evokedresponse curve 1104 begins at a particular cochlear depth (e.g., aroundfirst insertion depth 1004-1) to decrease at a rate greater thanexpected decrease rate 1106 as the cochlear depth of intracochlearelectrode 112-1 increases (e.g., as lead 110 is inserted into cochlea802). Specifically, at first insertion depth 1004-1, monitoring system600 may monitor a first evoked response 1108-1, while at secondinsertion depth 1004-2, monitoring system 600 may monitor a secondevoked response 1108-2 that is smaller in amplitude than first evokedresponse 1108-1. If a change 1110 between first evoked response 1108-1and second evoked response 1108-2 is greater than a predeterminedthreshold (e.g., 0 uV, 1 uV, 10 uV, etc.) combined with an expecteddecrease 1112 (e.g., a decrease based on expected decrease rate 1106 foreach unit of distance beyond high frequency target depth 1002 thatsecond insertion depth 1004-2 is located), monitoring system 600 maydetermine that cochlear trauma has likely occurred at a particularcochlear depth between first insertion depth 1004-1 and second insertiondepth 1004-2. For example, monitoring system 600 may determine thatcochlear trauma has likely occurred at second insertion depth 1004-2. Asdescribed above in relation to FIG. 7, monitoring system 600 may, inresponse to detecting the likely cochlear trauma, notify a user ofmonitoring system 600 (e.g., the surgeon performing insertion procedure1000) that cochlear trauma has likely occurred at the particularcochlear depth between first insertion depth 1004-1 and second insertiondepth 1004-2 (e.g., at second insertion depth 1004-2) within cochlea802.

As yet another example of monitoring cochlear trauma, a particularfrequency may be encoded within a cochlea at a low frequency targetdepth of the cochlea, the low frequency target depth located nearerwithin the cochlea to the apex of the cochlea than a final insertiondepth at which the intracochlear electrode is to be positioned when theinsertion procedure is completed, and a monitoring system may determinethat a change between a first evoked response and a second evokedresponse is greater than a predetermined threshold by determining that aphase of the second evoked response is different from a phase of thefirst evoked response by an amount greater than the predeterminedthreshold.

The phase of an evoked response numerically describes the relationshipbetween timing of the evoked response (e.g., the timing of peaks of theevoked response) relative to timing of the incoming acoustic stimulationcausing the evoked response (e.g., the timing of peaks of acousticstimulation generated by loudspeaker 302). For a pure tone, the phase ofthe evoked response may be described in radians or degrees if the delaybetween input peaks (i.e. peaks of the acoustic stimulation) and outputpeaks (i.e. peaks of the evoked response) is scaled by the inter-peakperiod for each waveform. For a more complex waveform, the phase canalso be described in terms of a phase delay, measured in milliseconds.

Because the phase is inherently a cyclic measure, phase delay measuredbased on phase alone is not unique. For example, a phase delay of P anda phase delay of P+C may result in the same phase if C represents theperiod of the incoming signal. Consequently, phase delay estimation mayneed to consider either an evoked response from an early part of thewaveform (an onset response) or a more complex stimulus. The techniquesfor doing so shall be apparent to those skilled in the art.

In a healthy cochlea, a phase of an evoked response signal recordedwithin the cochlea may be expected to change methodically in accordancewith the location within the cochlea (e.g., the cochlear depth) of theelectrode as the electrode is inserted apically (e.g., during aninsertion procedure such as insertion procedures 800 and/or 1000).Specifically, it may be expected that the phase will increase in a waythat is consistent with an increasing delay as the cochlear depth of theelectrode increases during the insertion procedure of the electrode intothe cochlea. Additionally, as the electrode approaches and/or passesnear the target frequency depth associated with the acoustic stimulation(e.g., high frequency target depth 1002), the phase may be expected tochange rapidly. Specifically, at the target frequency depth, the phasemay be significantly larger (e.g., 180 degrees larger) than the phase atmore basal locations passed by the electrode prior to the targetfrequency depth during the insertion procedure. It will also beunderstood that the phase of the intra-cochlearly recorded signal isdependent on the health of the outer hair cells. Functioning outer haircells sharpen the activity of the basilar membrane (especially at lowerSPL levels) and increase the phase delay at almost all cochlearlocations. The phase delay due to outer hair cells is particularlyextenuated near the frequency target depth associated with the frequencyof the acoustic stimulation.

Accordingly, a change in the phase of the intra-cochlear response duringthe insertion (e.g., from a first evoked response at a first cochleardepth to a second evoked response at a second cochlear depth nearer theapex of the cochlea) may be indicative of cochlear trauma. For example,a reduction in the amplitude of the response that is associated with thephase shift expected due to the location of the electrode relative tothe frequency of the acoustic stimulation may be associated with normalcochlear response and not due to cochlear trauma. Conversely, a changein the phase of the evoked response without a change to amplitude of theresponse may be indicative of cochlear trauma. For example, if the outerhair cells are damaged, the phase of the intra-cochlear response maychange in a way that is indicative of the decrease of the delay. This isbecause poorly functional outer hair cells may lead to decrease in thegain of the cochlear amplifier, and correspondingly a decrease in thephase delay. Because one would expect the delay to consistently increaseas one progresses the recording location more apically into the cochlea,a decrease in the phase delay during the insertion may be an indicatorof damage to the cochlea.

It should be noted that the changes in the phase of the response may bemore specifically indicative of damage when higher frequencies and lowersound pressure levels are used for the stimulation.

To illustrate, returning to FIG. 8, a particular frequency may beencoded within cochlea 802 at low frequency target depth of cochlea 802,which is located nearer within cochlea 802 to apex 806 of cochlea 802than final insertion depth 808. Monitoring system 600 may determine thata change between a first evoked response measured at insertion depth812-1 and a second evoked response measured at insertion depth 812-2 isgreater than a predetermined threshold. In particular, monitoring system600 may determine that a phase of the second evoked response isdifferent from a phase of the first evoked response by an amount greaterthan the predetermined threshold. If no cochlear trauma exists (e.g., ifno cochlear trauma occurs during insertion procedure 800), the phase ofthe evoked responses measured within cochlea 802 may be expected to beconstant independent of a cochlear depth at which the evoked responsesare measured. As such, if monitoring system 600 detects that the phasechanges from the first evoked response to the second evoked response,monitoring system 600 may determine that cochlear trauma has likelyoccurred at a particular location between first and second insertiondepths 812 (e.g., at second insertion depth 812-2) and may notify a user(e.g., a surgeon performing insertion procedure 800) that cochleartrauma has likely occurred at a particular insertion depth between firstand second insertion depths 812 (e.g., at second insertion depth 812-2).

As yet another example of monitoring cochlear trauma, monitoring system600 may determine that a change between a first evoked response measuredat a first insertion depth within the cochlea and a second evokedresponse measured at a second insertion depth within the cochlea, thesecond insertion depth nearer within the cochlea to the apex of thecochlea than the first insertion depth, is greater than a predeterminedthreshold. Specifically, monitoring system 600 may determine that thechange is greater than the predetermined threshold by determining thatthe second evoked response is smaller in amplitude than the first evokedresponse by an amount greater than the predetermined threshold, anddetermining that a phase of the second evoked response is within asecond predetermined threshold of a phase of the first evoked response.

To illustrate, FIG. 12 shows an exemplary insertion procedure 1200 oflead 110 into cochlea 802 of the patient. As explained above in relationto FIGS. 8 and 10, in FIG. 12, lead 110 may be included in a monitoringsystem (e.g., monitoring system 600 of FIG. 6 as implemented inimplementation 700 of FIG. 7) during insertion procedure 1200. Again,while omitted in FIG. 12 for clarity, lead 110 may include anextracochlear electrode (e.g., extracochlear electrode 702) that may becommunicatively coupled with a probe (e.g., probe 704) by way of a clipconnection (e.g., clip connection 706) that may be removably connectedto the extracochlear electrode as discussed above in relation to FIG. 7.Additionally, lead 110 may be communicatively coupled with a cochlearimplant (e.g., cochlear implant 108 in FIG. 7) which may receivedirection from a sound processor (e.g., sound processor 104 in FIG. 7)and/or from a programming system (e.g., programming system 402 in FIG.7), which may also be generating acoustic stimulation at a particularfrequency (e.g., using loudspeaker 302 in FIG. 7) as described above. Assuch, one of intracochlear electrodes 112 (e.g., intracochlear electrode112-1) may be shorted with the extracochlear electrode and maycommunicate evoked responses measured within cochlea 802 to the soundprocessor and/or to the programming system via the extracochlearelectrode, the probe, and/or other components of the monitoring system(e.g., an amplifier such as amplifier 708 in FIG. 7) that may serve aparticular implementation.

Insertion procedure 1200 is represented by an arrow indicating adirection that lead 110 may be inserted into cochlea 802 duringinsertion procedure 1200. During insertion procedure 1200, lead 110 maybe inserted into cochlea 802 beginning from outside base 804 until lead110 reaches final insertion depth 808, illustrated as a dotted lineextending through cochlea 802. Accordingly, in FIG. 12, lead 110 isshown to be partially, but not fully, inserted into cochlea 802,indicating that insertion procedure 1200 is ongoing.

As in previous examples, acoustic stimulation produced at a particularfrequency (e.g., a tone at the particular frequency) may be generated(e.g., by a loudspeaker such as loudspeaker 302 in FIG. 7) duringinsertion procedure 1200. Any suitable frequency may be used for theacoustic stimulation. For example, as shown in FIG. 12, the particularfrequency used for insertion procedure may be a similar or the samerelatively high frequency used in the example of insertion procedure1000, described above. Due to the tonotopic organization of auditorynerve tissue within cochlea 802 (see description in FIG. 2, above), theparticular frequency generated for insertion procedure 1200 may beencoded by auditory nerve tissue at a specific location (e.g., at aspecific depth) within cochlea 802. For example, the auditory nervetissue that encodes the particular frequency generated may be encoded byauditory nerve tissue denoted by Xs in FIG. 12. Because the particularfrequency used for insertion procedure 1200 may be a relatively highfrequency (e.g., 1000 Hz), the auditory nerve tissue that encodes theparticular frequency within cochlea 802 may correspond to (e.g., may belocated at) a high frequency target depth 1202 of cochlea 802. As shown,high frequency target depth 1202 may be located farther within cochlea802 from apex 806 of cochlea 802 than final insertion depth 808. Inother words, lead 110, including intracochlear electrode 112-1, mayreach and then pass high frequency target depth 1202 during insertionprocedure 1200.

During insertion procedure 1200, monitoring system 600 may monitorevoked responses that occur within cochlea 802 in response to theacoustic stimulation produced at the particular frequency (e.g., therelatively high frequency encoded by auditory nerve tissue located athigh frequency target depth 1202). More specifically, monitoring system600 may use intracochlear electrode 112-1 to measure a first evokedresponse at a first insertion depth 1204-1 and a second evoked responseat a second insertion depth 1204-2. As shown, first insertion depth1204-1 may be farther within cochlea 802 to apex 806 than high frequencytarget depth 1202, while second insertion depth 1204-2 may be nearerwithin cochlea 802 to apex 806 than high frequency target depth 1202.

Based on the measurements of evoked responses at first and secondinsertion depths 1204 and while insertion procedure 1200 is stillongoing, monitoring system 600 may determine that a change between thefirst evoked response measured at first insertion depth 1204-1 and thesecond evoked response measured at second insertion depth 1204-2 isgreater than a predetermined threshold. For example, monitoring system600 may determine that the second evoked response is smaller inamplitude than the first evoked response by an amount greater than thepredetermined threshold, or greater than the predetermined thresholdcombined with an expected decrease in the second evoked response foreach unit of distance beyond high frequency target depth 1202 thatsecond insertion depth 1204-2 is located. Moreover, monitoring system600 may determine that a phase of the second evoked response is within asecond predetermined threshold of a phase of the first evoked response.

If no cochlear trauma exists (e.g., if no cochlear trauma occurs duringinsertion procedure 1200), the phase of the evoked responses measuredwithin cochlea 802 may be expected to be constant at cochlear depthsfurther from apex 806 than high frequency target depth 1202 and constantat cochlear depths nearer to apex 806 than high frequency target depth1202. However, at high frequency target depth 1202, a phase at which theevoked responses are measured may change by an expected amount in anideal insertion procedure that causes no cochlear trauma. As such, ifmonitoring system 600 detects that the phase does not change by at leastan amount greater than the second predetermined threshold when theamplitude of the evoked response begins decreasing (e.g., when the highfrequency target depth 1202 is reached), monitoring system 600 maydetermine that cochlear trauma has likely occurred at second insertiondepth 1204-2, and may notify a user (e.g., a surgeon performinginsertion procedure 1200) that cochlear trauma has likely occurred atsecond insertion depth 1204-2).

FIG. 13 shows an exemplary graphical user interface 1300 that may bepresented by programming system 402 during an insertion procedure inwhich an electrode lead (e.g., lead 110) is inserted into a cochlea of apatient. As shown, graphical user interface 1300 includes an option 1302(which, in this example, is a drop-down menu option) that allows a userto select which intracochlear electrode is to be shorted with theextracochlear electrode during the insertion procedure. In theparticular example of FIG. 13, the user has selected an intracochlearelectrode labeled “E1” to be shorted with the extracochlear electrodeduring the insertion procedure. For example, the intracochlear electrodelabeled “E1” may correspond with intracochlear electrode 112-1 used inprevious examples (e.g., see FIG. 7). The user may easily select adifferent intracochlear electrode for shorting by selecting, forexample, the drop-down menu option 1302 and choosing a differentintracochlear electrode. Graphical user interface 1300 may furtherinclude an option 1304 that may be selected by the user to provide auser input command for monitoring system 600 to begin monitoring forevoked responses.

While monitoring system 600 monitors for evoked responses, programmingsystem 402 may present, within graphical user interface 1300, graphicalinformation associated with the evoked responses. For example, FIG. 14shows that programming system 402 may present a graph 1402 thatrepresents amplitudes of the evoked responses (e.g., similar to evokedresponse curves 902 or 904 of FIG. 9, or evoked response curves 1102 or1104 of FIG. 11), a graph 1404 that represents a current time domainwaveform of the evoked responses, and a graph 1406 that represents acurrent frequency domain waveform of the evoked responses. Additional oralternative graphical information associated with the evoked responsesmay be presented within graphical user interface 1300 as may serve aparticular implementation.

In certain embodiments, one or more of the processes described hereinmay be implemented at least in part as instructions embodied in anon-transitory computer-readable medium and executable by one or morecomputing devices. In general, a processor (e.g., a microprocessor)receives instructions, from a non-transitory computer-readable medium,(e.g., a memory, etc.), and executes those instructions, therebyperforming one or more processes, including one or more of the processesdescribed herein. Such instructions may be stored and/or transmittedusing any of a variety of known computer-readable media.

A computer-readable medium (also referred to as a processor-readablemedium) includes any non-transitory medium that participates inproviding data (e.g., instructions) that may be read by a computer(e.g., by a processor of a computer). Such a medium may take many forms,including, but not limited to, non-volatile media, and/or volatilemedia. Non-volatile media may include, for example, optical or magneticdisks and other persistent memory. Volatile media may include, forexample, dynamic random access memory (“DRAM”), which typicallyconstitutes a main memory. Common forms of computer-readable mediainclude, for example, a disk, hard disk, magnetic tape, any othermagnetic medium, a compact disc read-only memory (“CD-ROM”), a digitalvideo disc (“DVD”), any other optical medium, random access memory(“RAM”), programmable read-only memory (“PROM”), erasable programmableread-only memory (“EPROM”), electrically erasable programmable read-onlymemory (“EEPROM”), a Flash EEPROM device, any other memory chip orcartridge, or any other tangible medium from which a computer can read.

FIG. 15 illustrates an exemplary computing device 1500 that may bespecifically configured to perform one or more of the processesdescribed herein. As shown in FIG. 15, computing device 1500 may includea communication interface 1502, a processor 1504, a storage device 1506,and an input/output (“I/O”) module 1508 communicatively connected via acommunication infrastructure 1510. While an exemplary computing device1500 is shown in FIG. 15, the components illustrated in FIG. 15 are notintended to be limiting. Additional or alternative components may beused in other embodiments. Components of computing device 1500 shown inFIG. 15 will now be described in additional detail.

Communication interface 1502 may be configured to communicate with oneor more computing devices. Examples of communication interface 1502include, without limitation, a wired network interface (such as anetwork interface card), a wireless network interface (such as awireless network interface card), a modem, an audio/video connection,and any other suitable interface.

Processor 1504 generally represents any type or form of processing unitcapable of processing data or interpreting, executing, and/or directingexecution of one or more of the instructions, processes, and/oroperations described herein. Processor 1504 may direct execution ofoperations in accordance with one or more applications 1512 or othercomputer-executable instructions such as may be stored in storage device1506 or another computer-readable medium.

Storage device 1506 may include one or more data storage media, devices,or configurations and may employ any type, form, and combination of datastorage media and/or device. For example, storage device 1506 mayinclude, but is not limited to, a hard drive, network drive, flashdrive, magnetic disc, optical disc, RAM, dynamic RAM, other non-volatileand/or volatile data storage units, or a combination or sub-combinationthereof. Electronic data, including data described herein, may betemporarily and/or permanently stored in storage device 1506. Forexample, data representative of one or more executable applications 1512configured to direct processor 1504 to perform any of the operationsdescribed herein may be stored within storage device 1506. In someexamples, data may be arranged in one or more databases residing withinstorage device 1506.

I/O module 1508 may be configured to receive user input and provide useroutput and may include any hardware, firmware, software, or combinationthereof supportive of input and output capabilities. For example, I/Omodule 1508 may include hardware and/or software for capturing userinput, including, but not limited to, a keyboard or keypad, a touchscreen component (e.g., touch screen display), a receiver (e.g., an RFor infrared receiver), and/or one or more input buttons.

I/O module 1508 may include one or more devices for presenting output toa user, including, but not limited to, a graphics engine, a display(e.g., a display screen), one or more output drivers (e.g., displaydrivers), one or more audio speakers, and one or more audio drivers. Incertain embodiments, I/O module 1508 is configured to provide graphicaldata to a display for presentation to a user. The graphical data may berepresentative of one or more graphical user interfaces and/or any othergraphical content as may serve a particular implementation.

In some examples, any of the facilities or systems described herein maybe implemented by or within one or more components of computing device1500. For example, one or more applications 1512 residing within storagedevice 1506 may be configured to direct processor 1504 to perform one ormore processes or functions associated with monitoring facility 602.Likewise, storage facility 604 may be implemented by or within storagedevice 1506.

In the preceding description, various exemplary embodiments have beendescribed with reference to the accompanying drawings. It will, however,be evident that various modifications and changes may be made thereto,and additional embodiments may be implemented, without departing fromthe scope of the invention as set forth in the claims that follow. Forexample, certain features of one embodiment described herein may becombined with or substituted for features of another embodimentdescribed herein. The description and drawings are accordingly to beregarded in an illustrative rather than a restrictive sense.

What is claimed is:
 1. A system comprising: a cochlear implant; a leadconfigured to be coupled to the cochlear implant and to be inserted, byway of an insertion procedure, into a cochlea of a patient; a pluralityof electrodes disposed on the lead, the plurality of electrodesincluding: an intracochlear electrode of an array of intracochlearelectrodes disposed on a distal portion of the lead and configured to belocated within the cochlea when the insertion procedure is completed,and an extracochlear electrode configured to be located external to thecochlea when the insertion procedure is completed; a probe physicallyand communicatively coupled to the extracochlear electrode; and aprocessor communicatively coupled with the probe and the cochlearimplant, the processor configured to execute instructions to: direct thecochlear implant to short the intracochlear electrode with theextracochlear electrode, detect, during the insertion procedure and byway of the probe and the shorted intracochlear and extracochlearelectrodes, evoked responses measured at the intracochlear electrode inresponse to acoustic stimulation produced at a particular frequency, theevoked responses comprising: a first evoked response measured at a firstinsertion depth of the intracochlear electrode within the cochlea, and asecond evoked response measured at a second insertion depth of theintracochlear electrode within the cochlea, the second insertion depthnearer within the cochlea to an apex of the cochlea than the firstinsertion depth, and generate, during the insertion procedure and basedon the first and second evoked responses, a notification indicating thatcochlear trauma has likely occurred at the second insertion depth of theintracochlear electrode within the cochlea.
 2. The system of claim 1,wherein: the processor is further configured to execute the instructionsto receive a user input command to begin monitoring evoked responsesthat occur in response to the acoustic stimulation; and the directing ofthe cochlear implant to short the intracochlear and extracochlearelectrodes and the detecting of the evoked responses are performed inresponse to the user input command.
 3. The system of claim 2, whereinthe processor is implemented by a sound processor that iscommunicatively coupled both to the cochlear implant and to aprogramming system distinct from the sound processor, the programmingsystem configured to: present a user interface to a user during theinsertion procedure; and provide the user input command to the soundprocessor based on input received from the user by way of the userinterface.
 4. The system of claim 1, further comprising a loudspeakercommunicatively coupled to the processor and configured to present theacoustic stimulation to the patient at the particular frequency; whereinthe processor is further configured to execute the instructions todirect, during the insertion procedure and while the intracochlearelectrode is shorted with the extracochlear electrode, the loudspeakerto present the acoustic stimulation to the patient.
 5. The system ofclaim 4, wherein: the loudspeaker is implemented by a receiver of anelectro-acoustic stimulation (“EAS”) system; and the processor isimplemented by a sound processor included in the EAS system.
 6. Thesystem of claim 1, wherein the generating of the notification includes:identifying a change between the first evoked response measured at thefirst insertion depth and the second evoked response measured at thesecond insertion depth; determining that the identified change isgreater than a predetermined threshold; determining, based on thedetermination that the identified change is greater than thepredetermined threshold, that the cochlear trauma has likely occurred atthe second insertion depth; and notifying, in response to thedetermination that the cochlear trauma has likely occurred, a user thatthe cochlear trauma has likely occurred at the second insertion depth.7. The system of claim 1, wherein: the processor is implemented by asound processor that further includes an analog-to-digital converterconfigured to convert analog audio signals detected by a microphonecommunicatively coupled to the sound processor into digital audiosignals; and the sound processor is configured to record the evokedresponses measured at the intracochlear electrode by converting, usingthe analog-to-digital converter, the evoked responses detected by way ofthe probe and the shorted intracochlear and extracochlear electrodesfrom analog signals into digital signals.
 8. The system of claim 1,wherein: the particular frequency is encoded within the cochlea at a lowfrequency target depth of the cochlea, the low frequency target depthlocated nearer within the cochlea to the apex of the cochlea than afinal insertion depth at which the intracochlear electrode is to bepositioned when the insertion procedure is completed; and the generatingof the notification based on the first and second evoked responsesincludes determining that the second evoked response is smaller inamplitude than the first evoked response by an amount greater than apredetermined threshold.
 9. The system of claim 1, wherein: theparticular frequency is encoded within the cochlea at a high frequencytarget depth of the cochlea, the high frequency target depth locatedfarther within the cochlea from the apex of the cochlea than a finalinsertion depth at which the intracochlear electrode is to be positionedwhen the insertion procedure is completed; and the generating of thenotification based on the first and second evoked responses includesdetermining that the second evoked response is smaller in amplitude thanthe first evoked response by an amount greater than a sum of apredetermined threshold and an expected decrease in the second evokedresponse, the expected decrease determined based on a distance betweenthe high frequency target depth and the second insertion depth.
 10. Thesystem of claim 9, wherein the expected decrease in the second evokedresponse is approximately 1/e microvolts for each millimeter of distancebetween the high frequency target depth and the second insertion depth,wherein e is Euler's number.
 11. The system of claim 1, wherein: theparticular frequency is encoded within the cochlea at a low frequencytarget depth of the cochlea, the low frequency target depth locatednearer within the cochlea to the apex of the cochlea than a finalinsertion depth at which the intracochlear electrode is to be positionedwhen the insertion procedure is completed; and the generating of thenotification based on the first and second evoked responses includesdetermining that a phase of the second evoked response is different froma phase of the first evoked response by an amount greater than apredetermined threshold.
 12. The system of claim 1, wherein thegenerating of the notification based on the first and second evokedresponses includes: determining that the second evoked response issmaller in amplitude than the first evoked response by an amount greaterthan a first predetermined threshold; and determining that a phase ofthe second evoked response is within a second predetermined threshold ofa phase of the first evoked response.
 13. A method comprising: directinga cochlear implant to short an intracochlear electrode with anextracochlear electrode, wherein: the intracochlear and extracochlearelectrodes are included within a plurality of electrodes disposed on alead coupled to the cochlear implant and configured to be inserted intoa cochlea of a patient by way of an insertion procedure, theintracochlear electrode is from an array of intracochlear electrodeswithin the plurality of electrodes, the array of intracochlearelectrodes disposed on a distal portion of the lead and configured to belocated within the cochlea when the insertion procedure is completed,and the extracochlear electrode is configured to be located external tothe cochlea when the insertion procedure is completed; detecting, duringthe insertion procedure, evoked responses measured at the intracochlearelectrode in response to acoustic stimulation produced at a particularfrequency, wherein: the detecting of the evoked responses is performedby way of a probe physically and communicatively coupled to theextracochlear electrode while the extracochlear electrode is shorted tothe intracochlear electrode, and the evoked responses include: a firstevoked response measured at a first insertion depth of the intracochlearelectrode within the cochlea, and a second evoked response measured at asecond insertion depth of the intracochlear electrode within thecochlea, the second insertion depth nearer within the cochlea to an apexof the cochlea than the first insertion depth; and generating, duringthe insertion procedure and based on the first and second evokedresponses, a notification indicating that cochlear trauma has likelyoccurred at the second insertion depth of the intracochlear electrodewithin the cochlea.
 14. The method of claim 13, further comprisingreceiving a user input command to begin monitoring evoked responses thatoccur in response to the acoustic stimulation; wherein the directing ofthe cochlear implant to short the intracochlear and extracochlearelectrodes and the detecting of the evoked responses are performed inresponse to the user input command.
 15. The method of claim 14,performed by a sound processor that is communicatively coupled both tothe cochlear implant and to a programming system distinct from the soundprocessor, the programming system configured to: present a userinterface to a user during the insertion procedure; and provide the userinput command to the sound processor based on input received from theuser by way of the user interface.
 16. The method of claim 13, furthercomprising directing, during the insertion procedure and while theintracochlear electrode is shorted with the extracochlear electrode, aloudspeaker to present the acoustic stimulation to the patient at theparticular frequency.
 17. The method of claim 13, wherein the generatingof the notification includes: identifying a change between the firstevoked response measured at the first insertion depth and the secondevoked response measured at the second insertion depth; determining thatthe identified change is greater than a predetermined threshold;determining, based on the determination that the identified change isgreater than the predetermined threshold, that the cochlear trauma haslikely occurred at the second insertion depth; and notifying, inresponse to the determination that the cochlear trauma has likelyoccurred, a user that the cochlear trauma has likely occurred at thesecond insertion depth.
 18. The method of claim 13, performed by soundprocessor that includes an analog-to-digital converter configured toconvert analog audio signals detected by a microphone communicativelycoupled to the sound processor into digital audio signals; wherein thesound processor is configured to record the evoked responses measured atthe intracochlear electrode by converting, using the analog-to-digitalconverter, the evoked responses detected by way of the probe from analogsignals into digital signals.
 19. The method of claim 13, wherein: theparticular frequency is encoded within the cochlea at a low frequencytarget depth of the cochlea, the low frequency target depth locatednearer within the cochlea to the apex of the cochlea than a finalinsertion depth at which the intracochlear electrode is to be positionedwhen the insertion procedure is completed; and the generating of thenotification based on the first and second evoked responses includesdetermining that the second evoked response is smaller in amplitude thanthe first evoked response by an amount greater than a predeterminedthreshold.
 20. The method of claim 13, wherein: the particular frequencyis encoded within the cochlea at a high frequency target depth of thecochlea, the high frequency target depth located farther within thecochlea from the apex of the cochlea than a final insertion depth atwhich the intracochlear electrode is to be positioned when the insertionprocedure is completed; and the generating of the notification based onthe first and second evoked responses includes determining that thesecond evoked response is smaller in amplitude than the first evokedresponse by an amount greater than a sum of a predetermined thresholdand an expected decrease in the second evoked response, the expecteddecrease determined based on a distance between the high frequencytarget depth and the second insertion depth.